Our invention relates generally to apparatus employing disklike record media for the recording and/or reproduction of data, and in particular to apparatus for data transfer with flexible magnetic disks now commonly referred to as floppy disks, although we do not wish our invention to be unnecessarily limited to this particular type of record medium. The data transfer apparatus in accordance with our invention particularly features power saving facilities.
Floppy disks have found widespread acceptance in information processing and allied industries, as well as in offices in general, as compact data storage media. Being thin and limply flexible, the disks are usually encased in more rigid, apertured envelopes to make up disk assemblies or cartridges that are self supporting. There have also been suggested and used a variety of devices, known as floppy disk drives (FDDs), for data transfer to and from such disk cartridges. Dalziel et al. U.S. Pat. No. 3,678,481 and Castrodale et al. U.S. Pat. No. 4,089,029 represent examples of such known FDDs.
Usually FDDs are not self contained; they are subservient to host equipment typically comprising a central processor unit (CPU) and a controller. A familiar example of such mode of use is the daisy changing of two or more FDDs to a CPU via a controller, with the FDDs connected in parallel with each other. Each of the daisy chained FDDs has no power switch of its own; instead, a single power switch serves the complete system comprising the CPU, controller, and FDDs.
A problem has existed with this standardized power supply system. Not all the daisy chained FDDs are used for data transfer at one time, nor is any one FDD necessarily used for data transfer at all times, after the complete system is switched on. Conventionally, however, power has been fed to the various components of the FDDs even when they are not in actual use. This of course has incurred a substantial waste of energy.